I'm using fiber internet / 5mb upload, same issue occurs time by time. I will try to use Transporter app, but it looks like it has more agony than organizer.

"Unable to process app at this time due to a general error" is a server bug i think. Especially if you are trying to validate it appears after a while. On the other hand, if you try to upload your application, mostly it stucks at 90% or done without error. It is very weird.